The "central communications center" (teleprinter room), which appears several times in the film, is a highly accurate depiction. Nearly 30 historically correct original teleprinter machines, of various types, were used - some provided by collector / technical consultant Henning Treumann, and some borrowed from other sources. All the machines were fully operational, and, in the film, are all printing authentic archival messages from the Nazi era, fed from off-screen teletype machines and notebook computers.
Germany has strict laws against displaying the swastika, though artistic displays are specifically exempt. Filmmakers usually use incorrect swastikas to avoid causing public outrage. The producer wanted swastikas for authenticity, so the crew posted warnings around the filming locations. Still, a local resident filed an official complaint with the city, who pressed charges against the owners of some filming sites.
Initially, Germany's Ministry of Defense would not allow filming on Bendler Block. They relented after appeals from Tom Cruise and screenwriter/producer Christopher McQuarrie. The entire crew started every night of filming with a moment of silence in memory of Stauffenberg.
Much of the movie takes place in the offices of Bendlerblock which served as the offices for the military operations of the Third Reich's military command. The courtyard of Bendlerblock is where Colonel Claus Schenk Graf von Stauffenberg and the other conspirators were executed. Some of the filming of the movie took place at the actual building. This building is now the Memorial to the German Resistance (German: Gedenkstätte Deutscher Widerstand). The statement in the final slide of the movie is from a plaque near the site of execution at the Memorial.
David Bamber (Adolf Hitler) is the only non-German cast member who speaks with a German accent. The filmmakers felt that audiences would be distracted by Hitler speaking in Bamber's natural British accent.
The film's opening prologue is a quotation of a Nazi mandatory loyalty service oath for Soldiers of the German Armed Forces. It states: "I swear by God this sacred oath: That I shall render unconditional obedience to Adolf Hitler[,] Führer of the German Reich and people, Supreme Commander of the Armed Forces, And that I shall at all times be ready, as a brave soldier, to give my life for this oath . . . "
(at around 42 mins) When Christian Berkel's character is having the initial conversation with the other conspirators about the application of explosives and says "The trick is not to be around when they go off" is the same line David Niven says to Gregory Peck's character in The Guns of Navarone (1961).
Eleven extras playing Wehrmacht soldiers were injured on the set when they fell out of a moving lorry (truck). One suffered a serious back injury, the rest had bruises, cuts, and head injuries. An insurance company investigation concluded that an extra closed the side panel improperly, causing it to open while the lorry was in motion.
The film was originally scheduled for release on August 8, 2008, then moved up to June 27, 2008. The producer couldn't find a suitable location for the battle sequence in which Claus Schenk Graf von Stauffenberg loses his eye and hand, halting production and moving release to October 3, 2008. Filming resumed in June 2008, and release was moved to February 13, 2009. After a successful test screening, release was finally moved to December 25, 2008.
This is the second movie in which Kenneth Branagh, Kevin McNally and Ian McNeice have appeared together. The other was Conspiracy (2001). Both movies are based on true events from World War II and both are stories from the German side. Here they are Adolf Hitler's enemies, while in the other they are following Hitler's regime.
The song played over parts of the end credits (Track #1 on the soundtrack album, "They'll Remember You") uses lyrics from Johann Wolfgang Goethe's poem "Wanderers Nachtlied" ("Wanderer's Night Song"): "Ueber allen Gipfeln / Ist Ruh, / In allen Wipfeln / Spuerest du / Kaum einen Hauch. - Die Voegelein schweigen im Walde. / Warte nur, balde / Ruhest du auch." This translates into English as, "Over all the summits / it is calm. / In all the treetops / you can feel / hardly a breeze - The birds remain silent in the woods. / Just wait, soon / You'll rest as well."
This film hinges on the common belief that Hitler owed his survival to the last-minute change in venue from an underground bunker to the above-ground conference room. However, Mythbusters tested this myth and confirmed Hitler would've survived in either case.